1. Field of the Invention
The present invention relates to a detector for detecting an insufficient amount of oil in an internal combustion engine so as to stop the operation of the engine, or to give an alarm so as to prevent oil shortages, the oil detection being carried out by a simple structure which utilizes pressure changes in an oil case or oil pan of the engine.
2. Description of the Prior Art
Internal combustion engines for general use have been employed for use as simple, small prime movers such as a stationary engine or a portable generator engine.
Such internal combustion engines are in most cases unattended by personnel during the operation thereof. Further, the operators for such engines are sometimes unskilled, with insufficient knowledge of operation of the engine. Therefore, the engines are very likely to have attendant problems, such as seizures due to oil shortages therein.
One solution to such problems would be to equip the engines with electric oil level meters of the oil level detection type so as to prevent oil shortage. However, such type of meters are generally complicated in structure and relatively costly. The provision of such meters makes the engines more expensive, and use of the oil-level-detection type results in less precise measurements. If a conventional oil lever meter is employed, it will only indicate an amount of oil, and cannot itself detect oil shortages unless the operator reads the meter and confirms such oil shortage. Therefore, the above-mentioned problems which may occur due to oil shortages during unattended operation of the engine will remain unsolved.
The present invention provides a simple and effective solution for detection of oil shortages, which detection has conventionally been difficult to effect on the above-mentioned type of engines.
An important realization which should be noted in connection with the present invention is that internal combustion engines contain oil in the crankcases thereof, pressure pulsations are produced in the crank case by reciprocating movement of a piston of the engine, and such pressure pulsations are utilizable as an actuating medium for a detector.